for Journals by Title or ISSN
for Articles by Keywords
help
  Subjects -> ENGINEERING (Total: 1955 journals)
    - CHEMICAL ENGINEERING (153 journals)
    - CIVIL ENGINEERING (148 journals)
    - ELECTRICAL ENGINEERING (82 journals)
    - ENGINEERING (1111 journals)
    - ENGINEERING MECHANICS AND MATERIALS (290 journals)
    - HYDRAULIC ENGINEERING (45 journals)
    - INDUSTRIAL ENGINEERING (52 journals)
    - MECHANICAL ENGINEERING (74 journals)

CHEMICAL ENGINEERING (153 journals)                  1 2     

ACS Combinatorial Science     Full-text available via subscription   (Followers: 8)
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 3)
Acta Polymerica     Hybrid Journal   (Followers: 6)
Additives for Polymers     Full-text available via subscription   (Followers: 19)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 4)
Advanced Chemical Engineering Research     Open Access   (Followers: 8)
Advanced Powder Technology     Hybrid Journal   (Followers: 13)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 15)
Advances in Chemical Engineering and Science     Open Access   (Followers: 21)
Advances in Polymer Technology     Hybrid Journal   (Followers: 11)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 3)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 4)
Applied Petrochemical Research     Open Access   (Followers: 3)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (Followers: 6)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 8)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 5)
BMC Chemical Biology     Open Access   (Followers: 4)
Brazilian Journal of Chemical Engineering     Open Access   (Followers: 2)
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 1)
Carbohydrate Polymers     Hybrid Journal   (Followers: 8)
Catalysts     Open Access   (Followers: 6)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 7)
Chemical and Process Engineering     Open Access   (Followers: 3)
Chemical and Process Engineering Research     Open Access   (Followers: 5)
Chemical Communications     Full-text available via subscription   (Followers: 29)
Chemical Engineering & Technology     Hybrid Journal   (Followers: 24)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (Followers: 10)
Chemical Engineering and Science     Open Access   (Followers: 2)
Chemical Engineering Communications     Hybrid Journal   (Followers: 10)
Chemical Engineering Journal     Hybrid Journal   (Followers: 18)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 15)
Chemical Engineering Science     Hybrid Journal   (Followers: 10)
Chemical Geology     Hybrid Journal   (Followers: 9)
Chemical Papers     Hybrid Journal   (Followers: 3)
Chemical Product and Process Modeling     Full-text available via subscription   (Followers: 3)
Chemical Reviews     Full-text available via subscription   (Followers: 275)
Chemical Society Reviews     Full-text available via subscription   (Followers: 28)
Chemical Technology     Open Access   (Followers: 4)
ChemInform     Hybrid Journal   (Followers: 3)
Chemistry & Industry     Hybrid Journal   (Followers: 2)
Chemistry Central Journal     Open Access   (Followers: 5)
Chemistry of Materials     Full-text available via subscription   (Followers: 189)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 6)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Chemical Letters     Full-text available via subscription   (Followers: 1)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemical Physics     Hybrid Journal   (Followers: 1)
Coke and Chemistry     Hybrid Journal  
Coloration Technology     Hybrid Journal   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 8)
Computer Aided Chemical Engineering     Full-text available via subscription   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 6)
Corrosion Reviews     Full-text available via subscription   (Followers: 4)
Crystal Research and Technology     Hybrid Journal   (Followers: 2)
Current Opinion in Chemical Engineering     Open Access   (Followers: 3)
Education for Chemical Engineers     Hybrid Journal   (Followers: 4)
European Polymer Journal     Hybrid Journal   (Followers: 41)
Fibers and Polymers     Full-text available via subscription   (Followers: 3)
Focusing on Modern Food Industry     Open Access   (Followers: 3)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 1)
Geochemistry International     Hybrid Journal  
Handbook of Powder Technology     Full-text available via subscription   (Followers: 2)
High Performance Polymers     Hybrid Journal  
Indian Chemical Engineer     Hybrid Journal   (Followers: 3)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 12)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 9)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (Followers: 16)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 4)
International Journal of Chemical and Petroleum Sciences     Open Access   (Followers: 1)
International Journal of Chemical Engineering     Open Access   (Followers: 6)
International Journal of Chemical Reactor Engineering     Full-text available via subscription   (Followers: 3)
International Journal of Chemical Technology     Open Access   (Followers: 3)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Food Science     Open Access   (Followers: 2)
International Journal of Industrial Chemistry     Open Access  
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 3)
International Journal of Science and Engineering     Open Access   (Followers: 7)
International Journal of Waste Resources     Open Access   (Followers: 5)
ISRN Chemical Engineering     Open Access   (Followers: 4)
ISRN Polymer Science     Open Access   (Followers: 11)
Journal of Applied Crystallography     Hybrid Journal   (Followers: 4)
Journal of Applied Electrochemistry     Hybrid Journal   (Followers: 7)
Journal of Applied Polymer Science     Hybrid Journal   (Followers: 174)
Journal of Biomaterials Science, Polymer Edition     Hybrid Journal   (Followers: 8)
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 6)
Journal of Chemical Ecology     Hybrid Journal   (Followers: 1)
Journal of Chemical Engineering     Open Access   (Followers: 4)
Journal of Chemical Engineering and Materials Science     Open Access  
Journal of Chemical Science and Technology     Open Access   (Followers: 1)
Journal of Chemical Sciences     Partially Free   (Followers: 15)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 2)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 9)
Journal of Coatings     Open Access   (Followers: 2)
Journal of Crystallization Process and Technology     Open Access   (Followers: 5)
Journal of Food Measurement and Characterization     Hybrid Journal  
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (Followers: 5)
Journal of Fuels     Open Access  
Journal of Geochemical Exploration     Hybrid Journal  

        1 2     

Journal Cover Chemical Engineering Science
   Journal TOC RSS feeds Export to Zotero [12 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0009-2509
     Published by Elsevier Homepage  [2563 journals]   [SJR: 1.033]   [H-I: 103]
  • Computational exploration of metal–organic frameworks for CO2/CH4
           separation via temperature swing adsorption
    • Abstract: Publication date: 16 December 2014
      Source:Chemical Engineering Science, Volume 120
      Author(s): Zhengjie Li , Gang Xiao , Qingyuan Yang , Yuanlong Xiao , Chongli Zhong
      Molecular simulations were performed to investigate the performance of 151 metal–organic frameworks (MOFs) with large chemical and topological diversity on CO2/CH4 separation via temperature swing adsorption (TSA) process. The thermal regeneration energy was adopted in this work as an evaluation criterion and combined with other three commonly used ones (CO2 working capacity, adsorption selectivity and regenerability) to explore the structure–property relationships for the separation of the target system. The results show that the four evaluation criteria exhibit intimate correlations with the difference of adsorbility ( Δ A D ) of adsorbates but with non-concerted changing tendency. With a certain range of this parameter, it can be used as a good indicator for the preliminary screening of MOFs and the tailoring of new materials. Furthermore, from the structural database considered in current study, Cu-TDPAT with strong CO2 adsorption sites was found to possess the best performance by taking the thermal and water-stable properties into account.


      PubDate: 2014-09-21T20:24:40Z
       
  • EMMS-based discrete particle method (EMMS–DPM) for simulation of
           gas–solid flows
    • Abstract: Publication date: 16 December 2014
      Source:Chemical Engineering Science, Volume 120
      Author(s): Liqiang Lu , Ji Xu , Wei Ge , Yunpeng Yue , Xinhua Liu , Jinghai Li
      Understanding the hydrodynamics of gas–solid flows is a grand challenge in mechanical and chemical engineering. The continuum-based two-fluid models (TFM) are currently not accurate enough to describe the multi-scale heterogeneity, while the discrete particle method (DPM) following the trajectory of each particle is computationally infeasible for industrial systems. Following our previous work, we report in this article a coarse-grained DPM considering the meso-scale structure based on the energy-minimization multi-scale (EMMS) model, which can be orders of magnitude faster than the traditional DPM and can take full advantage of CPU–GPU (graphics processing unit) hybrid supercomputing. The size and solids concentration of the coarse-grained particles (CGP), as well as their interactions with the gas flow (the drag) are determined by the EMMS model with a two-phase decomposition. The interactions between CGPs are determined according to the kinetic theory of granular flows (KTGF). The method is tested by simulating the onset of fluidization and the steady state flow in lab-scale circulating fluidized bed (CFB) risers with different geometries and operating conditions both in 2D and 3D. The results agree well with experiments and traditional DPM based on single particles. The prospect of this method as a higher-resolution alternative to TFM for engineering applications and even for virtual process engineering is discussed finally.
      Graphical abstract image

      PubDate: 2014-09-21T20:24:40Z
       
  • Electro-coalescence of water drops in oils under pulsatile electric fields
    • Abstract: Publication date: 16 December 2014
      Source:Chemical Engineering Science, Volume 120
      Author(s): S.H. Mousavi , M. Ghadiri , M. Buckley
      Electric fields are commonly used to enhance the coalescence of water drops in oils. However, this process could cause some undesirable phenomena such as secondary droplets formation, reducing the separation efficiency. Here the effect of pulsatile electric fields (PEF) on the secondary droplets formation has been investigated. In the presence of a very low frequency PEF or DC electric field three distinct drop–drop and drop–interface interaction patterns are observed: complete coalescence, partial coalescence and rebound without coalescence. The first is the ideal pattern not leaving any secondary droplets. It has previously been shown that an increase in the electric field strength and/or a decrease in the interfacial tension result in non-ideal patterns in drop–interface coalescence. The application of PEF shifts the coalescence pattern from a non-ideal to an ideal one in both drop–drop and drop–interface coalescences. Three waveform types, i.e. square, half-sinusoidal and sawtooth waves have been applied to the coalescence process. It is shown that the sawtooth waveform is the most effective in reducing the secondary droplets formation in drop–interface coalescence, followed closely by the half-sinusoidal one. The observation of videos sequences suggests that a threshold frequency exists above which a non-ideal pattern switches to an ideal one. For drop–drop coalescence this threshold frequency depends on the PEF amplitude and the size of primary drop pairs, as for bigger primary drop pairs and larger amplitudes of PEF the threshold frequency would be higher. When using pulsatile electric fields higher field strengths can be applied for systems having high water content without causing field breakdown, as compared to the constant DC field. This is useful in optimizing the electro-coalescence process.


      PubDate: 2014-09-21T20:24:40Z
       
  • Numerical simulations of lateral solid mixing in gas-fluidized beds
    • Abstract: Publication date: 16 December 2014
      Source:Chemical Engineering Science, Volume 120
      Author(s): Oyebanjo Oke , Paola Lettieri , Piero Salatino , Roberto Solimene , Luca Mazzei
      We investigated the influence of design parameters and operational conditions on lateral solid mixing in fluidized beds adopting the Eulerian-Eulerian modeling approach. To quantify the rate at which solids mix laterally, we used a lateral dispersion coefficient ( D s r ). Following the usual approach employed in the literature, we defined D s r by means of an equation analogous to Fick׳s law of diffusion. To estimate D s r , we fitted the void-free solid volume fraction radial profiles obtained numerically with those obtained analytically by solving Fick׳s law. The profiles match very well. Our results show that D s r increases as superficial gas velocity and bed height increase; furthermore, it initially increases with bed width, but then remains approximately constant. The values of D s r obtained numerically are larger than the experimental ones, within the same order of magnitude. The overestimation has a twofold explanation. On one side, it reflects the different dimensionality of simulations (2D) as compared with real fluidized beds (3D), which affects the degrees of freedom of particle lateral motion. On the other, it is related to the way frictional solid stress was modeled: we employed the kinetic theory of granular flow model for the frictional solid pressure and the model of Schaeffer (1987) for the frictional solid viscosity. To investigate how sensitive the numerical results are on the constitutive model adopted for the frictional stress, we ran the simulations again using different frictional models and changing the solid volume fraction at which the bed is assumed to enter the frictional flow regime ( ϕ m i n ) . We observed that D s r is quite sensitive to the latter. This is because this threshold value influences the size and behavior of the bubbles in the bed. We obtained the best predictions for ϕ m i n = 0.50 . The results show that accurate prediction of lateral solid dispersion depends on adequate understanding of the frictional flow regime, and accurate modeling of the frictional stress which characterizes it.


      PubDate: 2014-09-21T20:24:40Z
       
  • Prediction of the mixing behaviour of binary mixtures of particles in a
           bladed mixer
    • Abstract: Publication date: 16 December 2014
      Source:Chemical Engineering Science, Volume 120
      Author(s): M. Halidan , G.R. Chandratilleke , S.L.I. Chan , A.B. Yu , J. Bridgwater
      The effects of particle size and density on the mixing behaviour of binary mixtures of spheres in a vertically-shafted bladed mixer are studied by means of the discrete element method. To characterise the mixing behaviour, a particle scale mixing index is used. The results reveal that for a given volume fraction, there are optimum small-to-large size ratio and light-to-heavy density ratio that can provide the maximum mixing index. That is, the particle size and density differences can interact with each other, sometimes improving mixing. The mechanism behind this mixing improvement is confirmed by the analysis of vertical forces on particles. The improvement occurs because large-heavy particles can sink to the vessel base under their heavy weight instead of being pushed upwards by the vertical force generated due to the size-difference. Small-light particles move on top of the large particles, improving the mixing behaviour. The volume fraction of the mixing particles also affects the mixing behaviour. The effects of particle size, density and volume fraction can be quantified in detail, and an empirical predictive equation to describe these effects is established for this purpose based on the simulated results. The equation can be used to determine the particle size and density ratios that result in an identical mixing quality, generating a comprehensive picture about the size and density equivalence in relation to mixing. Such a quantitative description is promising in application in that the present mixing system with its simple geometry can be used as a standard reference mixer for quantifying the effects of particle properties.


      PubDate: 2014-09-21T20:24:40Z
       
  • Flooding limit in countercurrent gas–liquid structured packed
           beds—Prediction from a linear stability analysis of an Eulerian
           two-fluid model
    • Abstract: Publication date: 16 December 2014
      Source:Chemical Engineering Science, Volume 120
      Author(s): I. Iliuta , F. Larachi , M. Fourati , L. Raynal , V. Roig
      Countercurrent flooding limits in gas–liquid structured packed bed columns were studied using a stability analysis of the solutions of a transient two-zone two-fluid hydrodynamic model around a uniform state. The model is based on the volume-average mass and momentum balance equations and the double-slit drag closures. The source terms in momentum balance equations refer to the total phase interaction and mechanical dispersion forces and the closure expression relating the gas and liquid pressures is given by capillary dispersion and gravity. The model predicts very well the flooding limits for air–water countercurrent flow through various Mellapak structured packings. The incidence on the column-limited flooding point of packing geometry (porosity and specific surface area), fluid throughputs and properties (viscosity, gas and liquid densities) and liquid spreading characteristics was discussed from the perspective of model simulated trends. Gravity was unveiled as the most important factor in the stabilization force which contributes to the attenuation of liquid waves inducing a tendency to make the flow more uniform. Its contribution was factored in using a modified capillary pressure model. Beside gravity, this formulation indicated that the stabilizing role of capillary forces could not be disregarded, particularly for lower values of the gravity scaling factor in liquid-rich regions at relatively high liquid flow rates.


      PubDate: 2014-09-21T20:24:40Z
       
  • A generalization of the virtual components concept for numerical
           simulation of multi-component isotope separation in cascades
    • Abstract: Publication date: 16 December 2014
      Source:Chemical Engineering Science, Volume 120
      Author(s): Shi Zeng , Lu Cheng , Dongjun Jiang , Valentin Borisevich , Georgy Sulaberidze
      The total flow of the optimal isotope separation cascade should be kept at a minimum to ensure economic viability. The concept of virtual components has proven useful in optimizing and designing cascades for multi-component isotope separation, but is only used in cases with an available analytical solution. Practical situations are complicated and resort to numerical simulations because there are no analytical solutions. Therefore, a generalization for numerical methods is required. A major difficulty in generalization is that mass conservation requires the concentration of a virtual component to be zero, which causes numerical problems. This paper proposes an approach to overcome this difficulty and develops a numerical method accordingly. The matched-R cascade is used as an example for numerical experiments to show that a cascade is solely determined by the choice of the two virtual components, and to demonstrate how the numerical method is applied to find the optimal cascade.


      PubDate: 2014-09-21T20:24:40Z
       
  • A comprehensive study on the kinetics, mass transfer and reaction
           engineering aspects of solvent-free glycerol hydrochlorination
    • Abstract: Publication date: 16 December 2014
      Source:Chemical Engineering Science, Volume 120
      Author(s): Cesar A. de Araujo Filho , Kari Eränen , Jyri-Pekka Mikkola , Tapio Salmi
      The thorough kinetic study of the solvent-free hydrochlorination of glycerol using gaseous hydrogen chloride in a laboratory-scale semibatch reactor was carried out. A wide set of experiments was performed where reaction temperature (70–120°C), catalyst concentration (0–50% by moles) and partial pressure (0.25, 0.5, 0.75 and 1.0atm) were varied. Acetic acid was used as a homogenous catalyst. A more accurate approach was given to the semibatch reactor modeling since it was demonstrated that the liquid volume significantly increased along the reaction. The concentration of HCl was determined experimentally and it was possible to observe the influence of the reaction parameters on the HCl uptake. It was also evidenced that a non-catalytic hydrochlorination takes place in the system and its effect is non-negligible, especially at high temperatures. A new kinetic model was proposed and tested in order to explain the experimental observations. Non-linear regression analysis was successfully applied on the experimental data and the modeling results showed a satisfactory agreement. The model was able to estimate the activation energies for both catalyzed and non-catalyzed experiments. A new concept named Catalyst Modulus was derived from the kinetic equations and then verified with experimental data; the fit of this parameter was very high, thus, pointing out the validity of the model.


      PubDate: 2014-09-21T20:24:40Z
       
  • Performance study of composite silica gels with different pore sizes and
           different impregnating hygroscopic salts
    • Abstract: Publication date: 16 December 2014
      Source:Chemical Engineering Science, Volume 120
      Author(s): X. Zheng , T.S. Ge , R.Z. Wang , L.M. Hu
      Composite solid desiccant materials are fabricated by impregnating hygroscopic salts into pores of different silica gels. In this paper, sorption characteristics of composite desiccants with different pore sizes (namely, 2–3nm, 7–8nm and 9–10nm) of silica gels and different salts in terms of LiCl, LiBr and CaCl2 are tested and analyzed. Researches on nitrogen adsorption suggest that, due to impregnated salt particles, composite desiccants are different from those of pure silica gels and have smaller surface area and pore volume. Sorption isotherms and sorption kinetics with respect to different composite desiccant materials are tested and fitted with the Dubinin–Astakhov (D–A) equation and the Linear Driving Force (LDF) model, respectively. Results showed that both the pore size of silica gel substrates and categories of impregnated salts affect the sorption characteristics of composite desiccants. Microporous silica gel with pore size of 2–3nm is not fit for preparing composite desiccants due to decreased water sorption quantity and sorption rate. Type B and mesoporous silica gels can be a promising host matrix of composite desiccant owing to enhanced water sorption quantity and favorable sorption rate. In addition, composite desiccants employing LiCl have the best sorption properties, while CaCl2 and LiBr follow next.


      PubDate: 2014-09-17T20:16:23Z
       
  • Erratum to “Mass transfer characteristics of bubbly flow in
           microchannels” [Chem. Eng. Sci. 109 (2014) 306–314]
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Lu Yang , Jing Tan , Kai Wang , Guangsheng Luo



      PubDate: 2014-09-17T20:16:23Z
       
  • Assessing the use of NMR chemical shifts for prediction of VLE in
           non-ideal binary liquid mixtures
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Q. Zhu , G.D. Moggridge , T. Dalton , J. Cooper , M.D. Mantle , L.F. Gladden , C. D׳Agostino
      A method of estimating vapour liquid equilibrium (VLE) using NMR chemical shift data has been proposed by Xu et al. (2012). This method is based on the concept that the average local composition around each species is determined by the thermodynamics of the system, and also determines the screening of the NMR active groups within that molecule, and so their NMR chemical shifts. Xu et al. (2012)׳s method has been replicated and verified; results are confirmed to be accurate for alcohol+hydrocarbon mixtures, giving VLE predictions of comparable accuracy to the UNIFAC, generally considered the best predictive activity coefficient model available. However, for more strongly non-ideal mixtures, the method becomes less reliable, giving significantly less accurate predictions of total pressure than UNIFAC. Several causes for this are identified. The model proposed by Xu et al. (2012) is unable to fit minima or maxima in chemical shifts, which are observed experimentally in some binary mixtures. Different NMR resonances within the same molecule lead to different predictions of VLE, clearly an un-physical result. The thermodynamics of strongly non-ideal mixtures are determined by more complex interactions than a simple description of average local composition around each component in the mixtures, for example strong and directional hydrogen bonds. Different groups within the same molecule may have different local compositions in their immediate vicinity; for example in the case of alcohol+water mixtures, one would expect a clustering of water molecules around the hydroxyl group but not the aliphatic group. Hence, the concept of a simple local composition model is not valid for these more complex cases, and it is therefore not surprising that a model based on this simple concept is often not effective in predicting VLE.
      Graphical abstract image

      PubDate: 2014-09-17T20:16:23Z
       
  • Reply to the comments on “Assessing the use of NMR chemical shifts
           for prediction of VLE in non-ideal binary liquid mixtures” by C.
           D׳Agostino
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Yingjie Xu



      PubDate: 2014-09-17T20:16:23Z
       
  • A reduced order PBM–ANN model of a multi-scale PBM–DEM
           description of a wet granulation process
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Dana Barrasso , Ashutosh Tamrakar , Rohit Ramachandran
      Wet granulation is a particle design process, often used in the pharmaceutical, consumer product, food, and fertilizer industries. A better process understanding is needed to improve process design, control, and optimization. Predominantly, two modeling frameworks are implemented to simulate granulation processes: population balance modeling (PBM) and discrete element methods (DEM). While PBM simulates changes in the number of particles in each size class due to rate processes such as aggregation, DEM tracks each particle individually, with the abilities to simulate spatial variations and collect mechanistic data. In this bi-directional coupled approach, the computational expenditure of the full model is overwhelmed by the high-fidelity DEM algorithm that needs to solve a set of ODEs for each and every particle being handled in the system for very small time intervals. To mitigate this computational inefficiency, reduced order modeling (ROM) is used to replace the computationally expensive DEM step. An artificial neural network (ANN) was trained using DEM results to relate particle size, size distribution, and impeller speed to the collision frequency. Results showed a high correlation between the trained ANN predictions and DEM-generated data. The ANN was coupled with a PBM as a key component of the aggregation rate kernel. The coupled model showed a different development of average particle size and size distribution over time from that of a constant aggregation rate kernel. In addition, the coupled model demonstrated sensitivity to the impeller speed via the ANN rate kernel. When compared with the fully coupled PBM–DEM model for accuracy and computation time savings, the hybrid PBM–ANN model demonstrated excellent agreement with DEM simulations at fractions of the original computational time.


      PubDate: 2014-09-17T20:16:23Z
       
  • Investigation of washing and storage strategy on aging of Mg-aminoclay
           (MgAC) coated nanoscale zero-valent iron (nZVI) particles
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Yuhoon Hwang , Young-Chul Lee , Paul D. Mines , You-Kwan Oh , Jin Seok Choi , Henrik R. Andersen
      The tendency towards agglomeration and oxidation of nanoscale zero-valent iron (nZVI) particles limits its application for in situ groundwater and soil remediation. Although the effect of surface coatings on nanoparticle stabilization has been commonly practiced, the effect of preparation procedures on aging of stabilized nZVI needs to be investigated. The effect of washing and storage, up to seven days, on aging of Mg-aminoclay (MgAC) coated nZVI is evaluated, following three procedures: pre- and post-storage washing with a 1mM NaHCO3 solution, and pre-storage washing with a stabilizer (MgAC) solution. Even though the initial particle size is identical, the observed size of pre-washed nZVI increases up to six times. This high aggregation tendency appears to be due to the desorption of MgAC during washing and storage, as verified by a decrease in the zeta potential, indicating a decrease of repulsion between nZVI particles. On the other hand, pre-storage washing is essential, in order to retain nZVI reactivity, by removal of residual reactants in the synthesis mixture. The reactivity of nZVI is examined with three parameters: optical density at 508nm as a measure of particle concentration, reactive iron content measured by H2 generation with acid digestion, and nitrate reduction capacity. All three parameters decrease significantly for post-storage washed nZVI, which corresponds to XRD results that exhibit transformation of Fe(0) to iron oxides. The reactivity tests display high linear correlations (r 2>0.95, p<0.05) with respect to one another. Pre-storage washing, followed by addition of MgAC, exhibits high stability as pre-storage washing, as well as high reactivity as post-storage washing. Here, it is found that the proper washing procedure is crucial in coated nZVI preparation, to provide long lasting stability and to maintain reaction capacity during its preparation and transport.
      Graphical abstract image

      PubDate: 2014-09-17T20:16:23Z
       
  • New structure-based model for Eulerian simulation of hydrodynamics in
           
    • Abstract: Publication date: 16 December 2014
      Source:Chemical Engineering Science, Volume 120
      Author(s): A.H. Ahmadi Motlagh , John R. Grace , Martha Salcudean , C.M. Hrenya
      The well-documented inaccuracy of conventional two-fluid modeling of hydrodynamics in fluidized beds of Geldart Group A particles is revisited. A new force-balance (FB) sub-grid-scale model, applied to the conventional Wen–Yu drag correlation, analyzes the balance of van der Waals, drag, gravity and buoyancy forces. It predicts formation of agglomerates inside the bed, updating the drag calculations by applying a correction factor to the conventional drag models to account for agglomerate formation. Good predictions were obtained of fluidization regimes and bed expansion, and there was promising agreement with experimental time-average radial voidage profiles reported by Dubrawski et al. (2013). Good quantitative agreement between DEM and two-fluid predictions of minimum bubbling velocity was also observed when the model was used to predict minimum bubbling velocity, in contrast to the predictions from a non-cohesive, Wen–Yu model. Further evaluation studies are required to test the ability of the new model to predict the properties of larger-scale fluidized beds.


      PubDate: 2014-09-17T20:16:23Z
       
  • Comparison of full-loop and riser-only simulations for a pilot-scale
           circulating fluidized bed riser
    • Abstract: Publication date: 16 December 2014
      Source:Chemical Engineering Science, Volume 120
      Author(s): Tingwen Li , Jean-François Dietiker , Lawrence Shadle
      In this paper, both full-loop and riser-only simulations of a pilot-scale circulating fluidized bed (CFB) system carried out by the open-source code MFIX (Multiphase Flow with Interphase eXchanges) are presented. Detailed comparison between full-loop and riser-only numerical simulations has been conducted with respect to the flow hydrodynamics inside the riser. The mean solids circulation rate is found to be the most critical parameter for both riser-only and full-loop simulations. On one hand, the mean solids circulation rate is needed for specifying the solids inlet boundary condition for the riser-only simulation. On the other hand, a reasonable prediction of the solids circulation rate is a prerequisite for the full-loop simulation to properly predict the flow hydrodynamics inside the riser. To better account for the full-loop dynamics in the riser-only simulation, the transient solids circulation rate measured from an experimental facility is imposed in the simulation in addition to the mean solids circulation rate. Consistent numerical predictions of the flow hydrodynamics inside the riser are obtained by different types of simulations. In-depth discussion on the advantage and disadvantages of each approach is presented and the riser-only simulation with appropriate boundary conditions is shown to be sufficient for investigating the steady CFB riser flow. The full-loop simulation is promising but more challenging as all major components and associated complicated physics have to be included and correctly modeled which require both advanced model capability and high computer power.


      PubDate: 2014-09-17T20:16:23Z
       
  • Preparation of black pigment with the Couette–Taylor vortex for
           electrophoretic displays
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Myeongho Kim , Kyung Ju Park , Kang Uk Lee , Myung Jun Kim , Woo-Sik Kim , Oh Joong Kwon , Jae Jeong Kim
      Carbon black is widely used as a black pigment in electrophoretic displays. The carbon black is required to control the density and surface charge depending on dielectric fluid to achieve a black image under the electric field. Both of them are closely related to the uniform polymer coating on the carbon black. Batch reactors have been used to carry out the polymerization on the carbon black. However, coating uniformity is not adequate when polymer coating is performed with a conventional batch system because it is difficult to maintain a uniform fluidic motion and mass transport throughout the batch reactor. Thus, a Couette–Taylor vortex reactor, generating uniform shear stress and fluidic motion, is used to coat the carbon black with a polymer. In this study, the influences of process variables in the Couette–Taylor vortex reactor on the properties of the synthesized black pigments are investigated. Because of strong agitation and uniform fluidic motion driven by the Couette–Taylor vortex, more uniform and smaller black pigments are obtained, resulting in the enhanced movement of the black pigment under an electric field. The productivity of the pigment is also improved along with the enhanced properties of the black pigments when using a continuous Couette–Taylor vortex reactor.


      PubDate: 2014-09-09T19:55:27Z
       
  • Two-dimensional numerical study of flow dynamics of a nucleated cell
           tethered under shear flow
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Zheng Yuan Luo , Long He , Shu Qi Wang , Savas Tasoglu , Feng Xu , Utkan Demirci , Bo Feng Bai
      When blood components (e.g., leukocytes and platelets) adhere to a surface (e.g., blood vessel wall), shear flow causes the elongation of the non-adherent part of the cell membrane forming a long thin cylinder shape (i.e., cell tether). The formation of cell tether is important for regulation of cell adhesion strength and stabilization of cell rolling, and may significantly affect the flow dynamics inside the vessel, as well as the motion of other cells and bioactive molecules. Although significant efforts have been made to reveal mechanisms underlying cell tether formation, the role of nucleus, nucleus/cell volume ratio, nucleus/plasma viscosity ratio and cytoplasm/plasma viscosity ratio remains unknown. As such, we developed a two-dimensional mathematical model, in which leukocytes are regarded as compound viscoelastic capsules with a nucleus. We investigated the effects of several factors on flow dynamic characteristics of tethered cells, including the cell length, the inclination angle, the drag and lift forces acting on the cell. The presence of a nucleus (with nucleus/cell volume ratio of 0.44) led to a decrease of 33.8% in the cell length and an increase of 152%, 113% and 43.6% in the inclination angle, the drag force and lift force respectively compared to those of a cell without nucleus. For a cell with nucleus/cell volume ratio of 0.2, a 10-fold increase in cytoplasm/plasma viscosity ratio resulted in a decrease of 19.3% in the cell length and an increase of 93.9%, 155% and 131% in the inclination angle, the drag force and lift force respectively. These results indicate that nucleus and cytoplasm play a significant role in flow dynamics of nucleated cells tethered under shear flow. The developed mathematical model could be used to further understand the mechanisms of cell-adhesion related bioprocesses and to optimize the conditions for cell manipulation in microfluidics.


      PubDate: 2014-09-09T19:55:27Z
       
  • Effect of evaporation and agglomeration on droplet shape oscillations
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): P. Deepu , Saptarshi Basu
      The effects of evaporation and the presence of agglomerating nanoparticles on the oscillation characteristics of pendant droplets are studied experimentally using ethanol and aqueous nanoalumina suspension, respectively. Axisymmetric oscillations induced by a round air jet are considered. Wavelet transform of the time evolution of the 2nd modal coefficient revealed that while a continuous increase in the natural frequency of the droplet occurs with time due to the diameter regression induced by vaporization in the case of ethanol droplet, no such change in resonant frequency occurs in the case of the agglomerating droplet. However, a gradual reduction in the oscillation amplitude ensues as the agglomeration becomes dominant.


      PubDate: 2014-09-09T19:55:27Z
       
  • The first kinetic hydrate inhibition investigation on fluorinated
           polymers: Poly(fluoroalkylacrylamide)s
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Mohamed F. Mady , Jae Min Bak , Hyung-il Lee , Malcolm A. Kelland
      Fluorohydrocarbons such as fluoromethane are capable of forming gas hydrates at temperatures higher than that of hydrocarbons. Based on this observation, we surmised that the interaction with hydrate cavities might be stronger with fluoroalkyl groups than with alkyl groups of similar size, and that therefore polymers with fluoroalkyl groups might show improved kinetic hydrate inhibition compared to polymers with alkyl groups. We have synthesized three fluorinated alkylacrylamide polymers, poly(N-fluoroethylacrylamide) (R-P1F), poly(N-difluoroethylacrylamide) (R-P2F), poly(N-trifluoroethylacrylamide) (R-P3F) by reversible addition-fragmentation chain transfer (RAFT) polymerization, followed by the removal of the chain end chain transfer agent (CTA) fragments. Poly(N-n-propylacrylamide) (R-PNPAM) and the previously investigated poly(N-isopropylacrylamide) (R-PNIPAM) with similar molecular weight (MW) and molecular weight distribution (MWD) were also synthesized. We have carried out high pressure slow constant cooling rocking cell experiments with a structure II forming natural gas mixture on all the polymers at varying concentrations. In addition, cloud point studies have been carried out. It was observed that R-P2F gave a better performance compared to R-P1F but a lower performance compared to the non-fluorinated polymers R-PNIPAM and R-PNPAM. Testing the KHI effect of increasing the fluorination to 3 fluorine atoms in an acrylamide homopolymer of this class was not possible due to lack of water-solubility of the polymer. Further isothermal tests were performed on R-P2F and R-PNIPAM to clarify the significance of the performance ranking of the KHIs. It was also observed that the induction time of R-P2F at 2500ppm is higher compared to 1000ppm of the same KHI polymer which is a typical performance-concentration effect seen with other polymer KHI classes.


      PubDate: 2014-09-09T19:55:27Z
       
  • New simple indices for risk assessment and hazards reduction at the
           conceptual design stage of a chemical process
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Mohammad Hossein Ordouei , Ali Elkamel , Ghanima Al-Sharrah
      Inherent safety has been of great interest to regulators, process designers and investors. The idea behind this is that a process design is more economic when it is inherently safer. Inherent safety is known as the safety intrinsic to a process; the spirit of which is to mitigate hazards within the process. It is also possible to achieve inherently safer design by diminishing the hazards in multi-component streams during process design. Hazards reduction during the design phase is a challenging task. A decrease in hazards in a process design not only improves process safety, but also protects the environment from potential impacts of the process. Current methodologies for risk assessment at the conceptual design stage of a chemical process need detailed process data, which is usually unavailable at such a phase. This paper presents simple new indices that require minimum data for risk evaluation of chemical processes at the conceptual design phase. The indices are applied to a hydrogenation case study to choose inherently safer designs among different alternatives. As an important result, total capacity of a process among other design array does not suffice for decision making unless the mass fraction of hazards in product streams are appreciably low.


      PubDate: 2014-09-09T19:55:27Z
       
  • Method of moments over orthogonal polynomial bases
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Naim Bajcinca , Steffen Hofmann , Kai Sundmacher
      A method for the design of approximate models in the form of a system of ordinary differential equations (ODE) for a class of first-order linear partial differential equations of the hyperbolic type with applications to monovariate and multivariate population balance systems is proposed in this work. We develop a closed moment model by utilizing a least square approximation of spatial-dependent factors over an orthogonal polynomial basis. A bounded hollow shaped interval of convergence with respect to the order of the approximate ODE model arises as a consequence of the structural and finite precision computation numerical errors. The proposed modeling scheme is of interest in model-based control and optimization of processes with distributed parameters.


      PubDate: 2014-09-09T19:55:27Z
       
  • IR laser assisted photothermal condensation in a microchannel
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Xuefeng He , Rong Chen , Qiang Liao , Hong Wang , Xun Zhu , Qingyun Xu , Shuzhe Li , Siyang Xiao
      In this work, the condensation behaviors of distilled water actuated by photothermal effect of the infrared laser with the wavelength of 1550nm in a microchannel were investigated through the visualization method and image processing technique. The impacts of the laser power and the laser spot position on the interface movement and slug formation were also explored. It is found that the interface tended to be advanced as a result of the photothermally induced evaporation–condensation–coalescence process at lower laser powers while the interface was firstly advanced at the beginning and then moved backward after the liquid slug formation in front of the interface at high laser powers. Experimental results also showed that higher laser power and smaller distance between the initial gas–liquid interface and fixed laser spot yielded faster advancing of the gas–liquid interface. For cases with the liquid slug formation, the growth rate of the liquid slug increased with increasing the laser power and decreasing the distance of the laser spot position away from the initial interface position as a result of a high evaporation rate.


      PubDate: 2014-09-09T19:55:27Z
       
  • Model identification and reduction for the control of an ice cream
           crystallization process
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Céline Casenave , Denis Dochain , Graciela Alvarez , Marcela Arellano , Hayat Benkhelifa , Denis Leducq
      Ice cream crystallization processes can be modeled by some population and energy balance equations. Due to the infinite dimensional and nonlinear characteristics, such models are highly complex, especially when all the phenomena of nucleation, growth and breakage are considered. Depending on the control problem under consideration, such a complexity can be useless and the control law can be designed on the basis of an input–output reduced order model of the process. In the present paper, we first consider a reduced order model of 6 ordinary differential equations obtained by the method of moments. By means of a sensitivity analysis and a parameter identification, it is shown that, to accurately describe the input–output behavior of the system whatever the conditions are, it is sufficient to change the values of only two parameters of this model, which is really interesting from a control point of view. However, when looking at the simulated data, the complexity of this moments model appears useless, from the input–output point of view. A second model reduction is therefore performed, based on physical assumptions. We finally get a new model with 3 ordinary differential equations, which is validated first on experimental data and then by comparison with the initial moments model.


      PubDate: 2014-09-09T19:55:27Z
       
  • Local characterization of a gas–solid fluidized bed in the presence
           of thermally induced interparticle forces
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Jaber Shabanian , Jamal Chaouki
      This article reports the results obtained from an extensive experimental campaign aimed at investigating the effect of interparticle forces (IPFs) on the local flow structure of a gas–solid fluidized bed. A polymer coating approach was used to enhance and control the degree of cohesive IPFs in a gas–solid fluidized bed. In this work, the local transient solids concentration (bed voidage) was carefully measured with the help of an accurate optical fiber probe at different temperatures and gas velocities covering both bubbling and turbulent fluidization regimes. Also, the Radioactive Particle Tracking (RPT) technique was employed to track the trajectory of a tracer mimicking the behavior of solid particles in two systems, one with the least amount of IPFs in the bubbling regime and the other with the highest amount. Experimental results showed that by increasing the level of IPFs in the bed the fixed bed and emulsion phase voidage in the bubbling regime increased and demonstrated higher capacities in holding gas inside their structures. In addition, the emulsion phase fraction increased, the tendency of the fluidizing gas passing through the bed in the emulsion phase enhanced in the bubbling regime, the frequency of the bubble/emulsion phase cycle decreased, and the meso-scale transition from bubbling to turbulent fluidization regime delayed until reaching higher superficial gas velocities.


      PubDate: 2014-09-09T19:55:27Z
       
  • Numerical investigation of droplet evaporation and transport in a
           turbulent spray with LES/VSJFDF model
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Xu Wen , Hanhui Jin , Ke Sun , Jianren Fan
      A velocity–scalar joint filtered density function (VSJFDF) transport equation was derived for the fluid flow field experienced by the particles in the evaporating gas–droplet two-phase flow. In this model, the large eddy simulation (LES) is used to simulate the fluid flow and the Lagrangian method is used to simulate the motion of the particle. In order to consider the sub-grid scale (SGS) effects of the gas velocity and scalar fluctuation transport and evaporation, we utilized the transport equation of the velocity–scalar joint filtered density function (VSJFDF) of the gas flow experienced by the droplets. With the developed LES/VSJFDF model, numerical simulations of an evaporating two-phase spray flow were carried out. The numerical results with the VSJFDF model, the VFDF (velocity filtered density function) model and non-FDF (filtered density function) model were compared with the experimental data, simultaneously. The comparison proved that the LES/VSJFDF model can definitely improve the accuracy of the prediction on the droplets׳ mean diameter.


      PubDate: 2014-09-09T19:55:27Z
       
  • Direct syntheses of a promising industrial organic–inorganic hybrid
           silica containing methanesulphonate
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Naiwang Liu , Xin Pu , Li Shi
      A simple procedure was developed for the synthesis of sulphonic group-functionalised silica material (SAM) under formic acid conditions without the presence of surfactant species or precursors. The organic–inorganic hybrid materials exhibited high catalytic activity and excellent thermal stability in the alkylation of aromatics with olefins. Pyridine-FTIR indicated that SAM has abundant Lewis acid sites, especially weak acid sites. 29Si and 27Al MAS NMR confirmed that aluminium methanesulphonate was anchored on the surface of the silica matrix by the covalent bond of Si–O–Al.
      Graphical abstract image Highlights

      PubDate: 2014-09-04T19:42:16Z
       
  • Thermal conductivity of Ionic Liquids: An estimation approach
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Johannes Albert , Karsten Müller
      Knowledge about the thermal conductivity of Ionic Liquids can be essential for research and process development. To compensate missing experimental data an estimation approach has been developed. Independency of other, also often unknown, substance properties was a major claim to this work. A structure interpolating approach was chosen assigning contributions to thermal conductivity to the ions. 375 Experimental data points for 39 Ionic Liquids have been collected and used for the development. The data for substances not used for the fitting could be estimated with an average absolute error of 4.99% (the error for substances used for parameter fitting was only 1.21%). A detailed error analysis resulted in a combined experimental and predictive uncertainty of 7.96% for unknown Ionic Liquids. Based on the proposed correlation a systematic screening of Ionic Liquids concerning thermal conduction is possible.
      Graphical abstract image

      PubDate: 2014-09-04T19:42:16Z
       
  • Control of incident irradiance on a batch operated flat-plate
           photobioreactor
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Razmig Kandilian , Tsu-Chin Tsao , Laurent Pilon
      This study experimentally demonstrated a feed-forward inversion control scheme for maintaining an optimum incident irradiance on photobioreactors (PBRs) during batch cultivation. A data-based model-free optimization using quadratic fit was utilized to rapidly estimate the optimum average fluence rate set point value that rendered maximum microalgae growth rate. Then, the feed-forward inversion control scheme adjusted the incident irradiance with respect to the in-process measured mass concentration to maintain the optimum average fluence rate inside the PBR. Optimization of growth conditions with respect to light is of prime importance for increasing biomass and lipid productivity in microalgae cultivation. The present approach can rapidly identify the optimum average fluence rate for any given species, reduce the lag time, and increase the growth rate and productivity of microalgae. This was illustrated with Nannochloropsis oculata batch grown in a flat-plate PBR illuminated from both sides.


      PubDate: 2014-09-04T19:42:16Z
       
  • Single phase fluid-stator heat transfer in a rotor–stator spinning
           disc reactor
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): M.M. de Beer , L. Pezzi Martins Loane , J.T.F. Keurentjes , J.C. Schouten , J. van der Schaaf
      Single phase fluid-stator heat transfer coefficients for a multi-stage rotor–stator spinning disc reactor are presented. The overall heat transfer coefficient is obtained by fitting experimentally obtained steady state outlet temperatures to an engineering model for the fluid flow inside the rotor–stator cavities. Heat transfer measurements are done for gap ratios of G=0.017 and 0.03, rotational Reynolds numbers of Re ω = 0 to 12×105 and superposed dimensionless throughflow rates of C w =211–421. From the overall heat transfer coefficient values for the fluid-stator Nusselt number Nu s are obtained. For all values of C w and G, Nu s increases more than a factor of 4 by increasing Re ω from 0 to 1.3×105. A throughflow dominated regime occurs for Re ω < 0.2 × 10 5 , where Nu s increases with increasing C w and decreasing G. For Re ω > 0.2 × 10 5 , rotation dominates the heat transfer and no influence of C w and G on Nu s is observed. The thermal performance of the multi-stage rotor–stator spinning disc reactor, quantified in the volumetric overall heat transfer coefficient, increases from U ov AV R − 1 = 0.46 ± 0.2 to 0.93±0.16MWm−3 K−1 by increasing Re ω from 0 to 4.5×105. The volumetric overall heat transfer coefficient of the multi-stage rotor–stator spinning disc reactor is more than a factor of 5 higher than in conventional tubular reactors.


      PubDate: 2014-09-04T19:42:16Z
       
  • Electrical capacitance volume tomography for imaging of pulsating flows in
           a trickle bed
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Aining Wang , Qussai Marashdeh , Brian J. Motil , Liang-Shih Fan
      Experimental results of the air–water pulsating flows in a trickle bed column were obtained using the electrical capacitance volume tomography (ECVT) system. Detailed 3-D pulse structures in both the fully developed and the transient conditions were illustrated. Pulse frequency, pulse traveling velocity, average liquid holdup and liquid holdup inside the gas-rich and liquid-rich regions, respectively, were measured. Based on a simplified model, the linear liquid velocities inside the gas-rich and liquid-rich regions were estimated. The results revealed that the gas flow rate was the most important parameter in controlling the pulsating flow properties. Discussion on the physical nature of the pulsating flow was also given.


      PubDate: 2014-09-04T19:42:16Z
       
  • Flow investigation in a microchannel with a flow disturbing rib
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): I.A. Stogiannis , A.D. Passos , A.A. Mouza , S.V. Paras , V. Pěnkavová , J. Tihon
      The purpose of this work is to study the flow around a flow-disturbing rib in a rectangular microchannel and to investigate the effect of key design parameters (i.e. the rib height and length as well as the Reynolds number) on the size of the reattachment length of the recirculation zones and the wall shear stress profiles in the vicinity of the rib. Initially the wall shear rate along the channel as well as the velocity field were experimentally determined using the electrodiffusion technique and the μ-PIV method, respectively. The experimental results are then used for validating a CFD code. Finally, the CFD code was employed for investigating the effect of the design parameters on the flow characteristics by performing a parametric study based on the Design of Experiments (DOE) and the Response Surface Methodology (RSM). It was found that the recirculation length in the laminar regime is affected mainly by the Re value and the rib height, whereas in the turbulent regime it is affected strongly by the rib height and slightly also by the rib length. Based on our results two new correlations, which can predict the length of the bottom recirculation zone with reasonable accuracy, are proposed and can be used for the design of microdevices.


      PubDate: 2014-09-04T19:42:16Z
       
  • Analysis of solid concentration distribution in dense solid–liquid
           stirred tanks by electrical resistance tomography
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Claudio Carletti , Giuseppina Montante , Tapio Westerlund , Alessandro Paglianti
      The knowledge of the spatial solids distribution is important for predicting the performance of various processes carried out in mechanically stirred equipment. In this work, the solid suspension in a stirred tank equipped with PBT and Lightnin A310 impellers is investigated by electrical resistance tomography (ERT). The analysis concerns dense solid–liquid systems, with mass ratio of suspended solid to liquid up to 0.43, with the main goal of obtaining detailed information on the spatial distribution of the dispersed phase and on the mixing quality. The shape of the interface between the solid mixture and the clear liquid layer is also determined. The results provide insight into the complex behaviour of dense suspensions and can be adopted as a benchmark for advanced modeling techniques based on CFD methods. Based on the experimental results, a method for the evaluation of the distribution of the solids under different working conditions and geometrical set-up is suggested. This criterion can provide a guideline for scale-up, when equal solid distribution at different scales is required.


      PubDate: 2014-09-04T19:42:16Z
       
  • Off-line optimization of baker׳s yeast production process
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Anne Richelle , Philippe Bogaerts
      A macroscopic model describing the influence of nitrogen on a fed-batch baker׳s yeast production process was used for the determination of optimal operating conditions in the sense of a production criterion. To this end, two different approaches were used: a control vector parameterization approach with mesh refinement and an approach based on the mathematical analysis of optimal operating policy (semi-analytical approach). The results of the two approaches lead to the determination of similar optimal operation conditions, which have been implemented for a new experimental phase. Moreover, these optimal conditions are in agreement with the profiles obtained by industrial manufacturers through an empirical optimization of the process (trial and error method). The model predictions are in good accordance with experimental data. This conclusion was supported by an uncertainty analysis on the model outputs with respect to the parameter estimation errors.


      PubDate: 2014-09-04T19:42:16Z
       
  • Crystal shape and size control using a plug flow crystallization
           configuration
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Joseph Sang-Il Kwon , Michael Nayhouse , Gerassimos Orkoulas , Panagiotis D. Christofides
      This work focuses on modeling and control of a continuous plug flow crystallizer (PFC) used to produce tetragonal hen-egg-white (HEW) lysozyme crystals and proposes an optimization-based control scheme to produce crystals with desired size and shape distributions in the presence of disturbances. Initially, a kinetic Monte Carlo (kMC) model is developed to simulate the crystal growth in a seeded PFC, which consists of five distinct segments. The crystal growth rate equations taken from (Durbin and Feher, 1986) are used in the kMC simulations for the modeling of the crystal growth in the direction of (110) and (101) faces. Then, a population balance equation (PBE) is presented to describe the spatio-temporal evolution of the crystal volume distribution of the entire crystal population, and the method of moments is applied to derive a reduced-order moment model. Along with the mass and energy balance equations, the leading moments that describe the dominant dynamic behavior of the crystal volume distribution are used in the optimization-based controller to compute optimal jacket temperatures for each segment of the PFC and the optimal superficial velocity, in order to minimize the squared deviation of the average crystal size and shape from the set-points throughout the PFC. Furthermore, a feed-forward control (FFC) strategy is proposed to deal with feed flow disturbances that occur during the operation of the PFC. Using the proposed optimization and control schemes, crystals with desired size and shape distributions are produced in the presence of significant disturbances in the inflow solute concentration and size distribution of seed crystals.


      PubDate: 2014-09-04T19:42:16Z
       
  • Preparation of proteolytic microreactors by freeze-drying immobilization
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Kyuya Nakagawa , Akihiro Tamura , Chaiyan Chaiya
      Protease from Bacillus licheniformis was immobilized in a freeze-dried poly(vinyl alcohol) (PVA) micromonolith directly prepared in the microchannels of a microreactor. The prepared PVA micromonoliths had porous microstructures of ~10–30μm in size. Five microreactors were prepared, with microchannels consisting of interconnected straight and elbow segments or a plain straight segment. The system performance was characterized in terms of proteolytic reaction activities. The reactors demonstrated continuous proteolytic activity for 9d with considerable reaction yields. The proteolytic performance was significantly influenced by the microchannel patterning, and was closely linked to the pressure drops in the reactors. The product distributions varied depending on the flow rates of the substrate solutions and the microchannel patterns. Fractions obtained from different reactors gave different product compositions even when operating under similar conditions and producing comparable yields.


      PubDate: 2014-09-04T19:42:16Z
       
  • Absorption of steam bubbles in lithium bromide solution
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Philip Donnellan , Kevin Cronin , William Lee , Shane Duggan , Edmond Byrne
      Absorption heat transformers are thermodynamic cycles that are capable of recycling waste heat energy by increasing its temperature. One of the most important unit operations in a heat transformer is the exothermic absorption of water vapour into a solution of choice at a higher temperature. Bubble columns are potentially an efficient means of achieving this. An experimental analysis is conducted which examines the absorption of single steam bubbles into a concentrated aqueous lithium bromide solution. The bubbles are tracked using a high speed camera, and their rate of absorption is modelled using a simple ordinary differential equation model. Accurate model predictions are obtained when oscillating bubble Nusselt and the Sherwood number correlations are utilised. The proposed model is capable of describing 96% of the observed experimental variability. Very large mass transfer coefficients of approximately 0.0012m/s are obtained, which is higher than any previously reported values used in heat transformer absorber design.


      PubDate: 2014-09-04T19:42:16Z
       
  • Oscillation dynamics of sessile droplets subjected to substrate vibration
    • Abstract: Publication date: 18 October 2014
      Source:Chemical Engineering Science, Volume 118
      Author(s): P. Deepu , Shubham Chowdhuri , Saptarshi Basu
      Sessile droplets on a vibrating substrate are investigated focusing on axisymmetric oscillations with pinned contact line. Proper orthogonal decomposition is employed to identify the different modes of droplet shape oscillation and quantitatively assess the droplet oscillation and spectral response. We offer the first experimental evidence for the analogy of an oscillating sessile droplet with a non-linear spring mass damper system. The qualitative and quantitative agreement of amplitude-response and phase-response curves and limit cycles of the model dynamical system with that observed experimentally suggest that the bulk oscillations in the fundamental mode of a sessile droplet can be very well modeled by a Duffing oscillator with a hard spring, especially near the resonance. The red shift of the resonance peak with an increase in the glycerol concentration is clearly evidenced by both the experimental and predicted amplitude response curves. The influence of various operational parameters such as excitation frequency and amplitude and fluid properties on the droplet oscillation characteristics is adequately captured by the model.


      PubDate: 2014-09-04T19:42:16Z
       
  • Table of Contents
    • Abstract: Publication date: 18 October 2014
      Source:Chemical Engineering Science, Volume 118




      PubDate: 2014-09-04T19:42:16Z
       
  • Added mass of a spherical cap body
    • Abstract: Publication date: 18 October 2014
      Source:Chemical Engineering Science, Volume 118
      Author(s): Miroslav Simcik , Miroslav Puncochar , Marek C. Ruzicka
      The added mass coefficient C was determined for a single spherical-cap body moving in a uniform unbounded fluid. An approximate simple physical model for C was suggested and was well compared with the analytical result of Kendoush, which likely is the only available theoretical result in the literature, up to date. The correct result for C was obtained via direct numerical flow simulation with CFD. Both the rigid and deformable (bubble, drop) cap body was considered. An approximate model was suggested for the collective added mass in a swarm of spherical cap bodies. A relation was found between the added mass of an unbounded cap body and a bounded spherical body. Practical explicit correlation formulas for C were obtained, suitable for engineering modelling of multiphase flow systems with bubbles, drops and solids. A relation between the added mass, Darwin drift, and fluid mixing was also noted.
      Graphical abstract image

      PubDate: 2014-09-04T19:42:16Z
       
  • Non-dimensionalization and three-dimensional flow regime map for
           fluidization analyses
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Kenya Kuwagi , Atsuto Kogane , Hiroyuki Hirano , Azri Bin Alias , Toshihiro Takami
      This article is on the dimensional analysis and the classification of fluidization from the viewpoint of numerical analysis. At first, the governing equations used in the DEM (Discrete Element Method) and CFD (Computational Fluid Dynamics) coupling model were non-dimensionalized with the method of Hellums and Churchill (1964). From the resulting dimensionless equations, it was concluded that the five dimensionless numbers, i.e. Re: Reynolds number, Ar: Archimedes number, Ga: Galilei number, Fr: Froude number and ρ ⁎: ratio of particle density divided by fluid one, can be derived and hydrodynamically dominant on the fluid behaviors. Further, these can illustrate the dimensionless numbers proposed in the previous studies. Secondary, a three-dimensional flow regime map of homogeneous, bubbling and turbulent fluidizations was proposed with these dimensionless numbers using the DEM–CFD simulations. Finally, the plane of Reynolds number, Re mb at the minimum bubbling fluidization velocity, u mb in the map can be proposed and expressed as, R e m b = 0.263 ρ ⁎ − 0.553 A r 0.612 . u mb can be estimated using this equation for various conditions.
      Graphical abstract image

      PubDate: 2014-09-04T19:42:16Z
       
  • Liquid ligament formation dynamics on a spinning wheel
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Benjamin Bizjan , Brane Širok , Marko Hočevar , Alen Orbanić
      A ligament-type disintegration of liquid on a spinning wheel was investigated experimentally using photographs taken by a high-speed camera. Three different Newtonian liquids were used at various flow rates and the wheel rotational speed was varied in a wide range. Velocity slip between the liquid film and the wheel surface was found to depend primarily on wheel rotational speed and angular position, dropping to approximately 1–1.5% for sufficiently fast rotation. As a liquid ligament grows from the film, the relative pathline of its free (head) end resembles an involute. Ligament strain rate on the film was found to increase steadily until the head droplet pinch-off when a short but significant strain rate reduction was observed. At this point, ligament is rapidly decelerated in the lateral direction which may cause significant longitudinal oscillations, possibly destabilizing its growth. Strain rate then increases again until the ligament detachment from the film which is soon followed by capillary breakup into droplets. The mean ligament length at detachment was determined to increase with a rising liquid flow rate and Ohnesorge number.


      PubDate: 2014-09-04T19:42:16Z
       
  • Influence of viscosity on the impingement of laminar liquid jets
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Jiakai Lu , Carlos M. Corvalan
      The impingement of low-viscosity liquid jets has been studied extensively for over a century due to their fundamental scientific interest and their practical importance in spray and atomization technologies. However, the role of the fluid viscosity in the impingement dynamics is largely unknown despite the fact that viscous liquids are common in spray and atomization processes ranging from spray drying in the food industry to the atomization of gelled propellants in rocket engines. Here, we report direct numerical simulations that enable a detailed analysis of the influence of viscosity on the impingement dynamics. The simulations solve the complete Navier–Stokes system governing the free-surface dynamics, and so fully account for the interplay of inertia, viscous and capillary forces. Results show that the liquid viscosity profoundly affects the impingement dynamics. The collision of viscous liquid jets generates a fluid sheet that thins at a rate r − 1 with the distance r from the impact point at intermediate viscosities, in contrast to the inertial case in which the sheet thins at a faster rate r − 2 . As the viscosity increases, the fluid sheets become thicker and more uniform, and contrary to the inertial case, the velocity of the sheets is lower than the velocity of the jets. Results further reveal that due to viscous stresses the impact pressure generated by the collision of viscous liquid jets scales as Re − 1 , where Re is the jet Reynolds number.


      PubDate: 2014-09-04T19:42:16Z
       
  • Transesterification of canola oil catalized by calcined Mg–Al
           hydrotalcite doped with nitratine
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): I. Córdova Reyes , J. Salmones , B. Zeifert , J.L. Contreras , F. Rojas
      Mg–Al hydrotalcite substrates having an X=Al+3/(Al+3+Mg+2) metal molar ratio equal to 0.2, were synthesized at pH=8 from a coprecipitation method combined with microwave radiation exposure to induce the crystalline network growth of the precursory hydrogel. The hydrotalcite materials were obtained either pristine or with the inclusion of nitratine at different amounts; this compound being added during the washing procedure of the hydrogel. The hydrotalcite substrates were calcined in air at 570°C for 18h, thus generating the corresponding mixed metal oxides. The final substrates were characterized by infrared spectroscopy, while also displaying the characteristic X-ray diffraction patterns of the hydrotalcite phase before calcination. The mixed metal oxide solids were used as catalysts (CI–CV) and were tested in the transesterification reaction of canola oil. It was found that the conversion to biodiesel increased, depending on the nitratine content existing in hydrotalcite as well as on the extension of the formed periclase phase. Among all catalysts, one of the substrates (containing 7wt% of nitratine) exhibited the highest conversion of canola oil to biodiesel (91%), which, in this material, can be attributed to the preponderant presence of periclase and promoting effect of Na2O. The latter material and a catalyst with no nitratine content were characterized by scanning electron microscopy, and their elemental surface composition was evaluated by Energy Dispersive X-ray Spectroscopy; in turn, their basic character was assessed by CO2 Temperature Programmed Desorption. The conversion of synthesized Fatty Acid Methyl-Esters was calculated from the area under the signal peaks registered by Nuclear Magnetic Resonance spectroscopy.
      Graphical abstract image

      PubDate: 2014-09-04T19:42:16Z
       
  • Transient numerical modeling of catalytic channels using a quasi-steady
           gas phase
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): P.M. Struk , J.S. T’ien , F.J. Miller , D.L. Dietrich
      This paper presents a transient model of internal catalytic combustion suitable for isolated channels and monolith reactors. Due to time-scales in the problem, the model considers a quasi-steady gas phase with a transient solid. The gas is described by axially varying bulk temperature and species. The gas includes lateral diffusion via transfer coefficients and the specification of a gas-phase species concentration at the wall; axial diffusion is neglected. The solid phase is a thermally thin shell with axially varying temperature, surface species, and surface species concentrations. The solid includes axial heat conduction and external heat loss by convection and radiation. The combustion process utilizes detailed gas and surface reaction models. The gas-phase model becomes a system of stiff ordinary differential equations with respect to axial position; the upstream (inlet) boundary conditions are specified and the axially varying solid properties are parameters in integration. The solid phase discretizes into a system of stiff ordinary differential-algebraic equations with respect to time. The time evolution of the system comes from alternating integrations of the quasi-steady gas phase and transient solid. The model is compared to two experimental cases using CO fuel: (1) steady-state conversion in an isothermal platinum tube and (2) transient propagation of a catalytic reaction inside a small platinum tube and includes external tube temperature measurements. This work presents sensitivity studies on important parameters including internal transfer coefficients, catalytic surface site density, external heat-loss, and others. Under mass-transfer limited conditions, global transfer coefficients are adequate to predict fuel conversion. Near light-off, the model predictions improve for the first case after adjusting the surface kinetics such that the net rate of CO adsorption increases compared to O2. For the second case, predictions of transient propagation speeds are good for equivalence ratios near unity and greater but require adjustment of external heat loss or kinetics to match under lean conditions.


      PubDate: 2014-09-04T19:42:16Z
       
  • Formation kinetics of cyclopentane–methane binary clathrate hydrate
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Lichao Cai , Brian A. Pethica , Pablo G. Debenedetti , Sankaran Sundaresan
      Clathrate hydrates with two guest species fitting different-sized cages can form at warm temperatures and/or low pressures, and this extended range of thermodynamic stability is favorable to many hydrate based applications. In the present study, the kinetics of formation and growth of cyclopentane–methane hydrate is studied at several temperatures ( T > 288 K) and pressures ( P < 3 MPa), where neither single-guest methane hydrate nor single-guest cyclopentane hydrate forms. Experiments were performed in a well-stirred vessel with water being available in excess of stoichiometric amount. Using the measured temperature and pressure trajectories, the temporal evolution of hydrate formation rate is deduced. As one would expect, the amount of hydrate formed in a prescribed time increases with the degree of subcooling. The rate of hydrate formation is shown to be limited by the rate of methane mass transfer.


      PubDate: 2014-09-04T19:42:16Z
       
  • Numerical study of coalescence and breakup in a bubble column using a
           hybrid volume of fluid and discrete bubble model approach
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Deepak Jain , J.A.M. Kuipers , Niels G. Deen
      In this work, two powerful methods are combined for bubble column simulations namely, the volume of fluid and the discrete bubble model. While the former method takes care of the free surface, the discrete bubble model tracks and handles the dynamics of the dispersed bubbles. The hybrid model presented in this work is verified and validated with existing established experimental results. A model parameter study for bubble break-up and coalescence is performed to find the optimum values of the model parameters, i.e. the critical Weber number and the coalescence calibration factor.
      Graphical abstract image Highlights

      PubDate: 2014-09-04T19:42:16Z
       
  • Experimental and CFD studies on the intensified micromixing performance of
           micro-impinging stream reactors built from commercial T-junctions
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Zhiwei Liu , Lei Guo , Tianhao Huang , Lixiong Wen , Jianfeng Chen
      A micro-impinging stream reactor (MISR) at the size of ~1mm has been built from commercial T-junctions and steel micro-capillaries, which has advantages of intensified micromixing and easy construction. By using a big-sized and very short outlet tube, the two injecting streams could impinge intensely within the limited chamber of the T-junction to achieve a quick mixing at the micro-scale. The effects of both operating parameters and geometric parameters of MISR, e.g., inlet jet Reynolds number (Re j ), volumetric flow ratio (R), outlet configuration, outlet length (L), and inlet diameter (d i ), on the micromixing efficiency have been studied by experiments with the Villermaux–Dushman reaction as well as by computational fluid dynamics (CFD) method. Both experimental and numerical results agreed well and demonstrated that the inlet jet Reynolds number (Re j ) and inlet size played a key role for the micromixing performance. The outlet configuration also had a great influence on micromixing, but the effects of the length of outlet channel were insignificant. This work showed that MISR will have a great potential for both reaction and separation process intensifications.


      PubDate: 2014-09-04T19:42:16Z
       
  • Analysis of mixing of impinging radial jets with crossflow in the regime
           of counter flow jet formation
    • Abstract: Publication date: 8 November 2014
      Source:Chemical Engineering Science, Volume 119
      Author(s): Е.V. Kartaev , V.А. Emel’kin , М.G. Ktalkherman , V.I. Kuz’min , S.М. Aul’chenko , S.P. Vashenko
      Experimental investigation and numerical calculation of the macromixing of multi-orifice impinging radial jets and main crossflow in the plasma-chemical reactor channel were performed. The emphasis is on the analysis of the conditions providing the formation of a jet on the channel axis directed toward the main flow. Axial and radial distributions of the temperatures were measured in four channel cross sections above the jets injection point. An empirical dependence is proposed to calculate the axial depth of penetration the counter flow jet. The dependence generalizes the measurement results and is in agreement with the data of other authors. The relationship between the parameter of counter flow jet penetration depth and the parameter of impinging jets radial depth of penetration was revealed. Experimental data are in qualitative agreement with the numerical simulation results.


      PubDate: 2014-09-04T19:42:16Z
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2014